Carefully Evaluate Disposal Options

Pork producers should be prepared to handle emergencies and not wait until large numbers of pigs suddenly die. As states continue to modify environmental rules, and the availability of rendering service continues to shrink, producers should seriously consider developing a plan to deal with emergency pig losses on their farms, according to an expert on the subject at Iowa State University (ISU). Tom

Pork producers should be prepared to handle emergencies and not wait until large numbers of pigs suddenly die.

As states continue to modify environmental rules, and the availability of rendering service continues to shrink, producers should seriously consider developing a plan to deal with emergency pig losses on their farms, according to an expert on the subject at Iowa State University (ISU).

Tom Glanville, professor in the Department of Agricultural and Biosystems Engineering at ISU, has studied soil and water issues related to livestock burial, and conducted on-farm composting research and demonstration projects for the swine and poultry industries.

Last year, Glanville and his research team at ISU and Pennsylvania State University completed a three-year study of the performance and environmental impacts of using composting for emergency disposal of cattle. Currently, they are studying biosecure composting practices for pigs for the Canadian Food Inspection Agency.

Short-Term Emergency Plan

“There is a big difference between losing your herd all in one day and losing a few pigs at a time. Due to the large mass of material to be disposed, and the resulting biosecurity and environmental concerns, your options are much more limited than for routine disposal of daily mortalities.

“Producers may be surprised by the number of potential roadblocks that can arise,” Glanville says. “Looking at the options and logistics, in advance of an emergency, can reduce frustration, costs and environmental and legal liabilities.”

Glanville provides this checklist to consider for emergency disposal of large numbers of dead stock:

Burial: “You are putting a lot of pollutants into the soil when you bury large numbers of carcasses, so environmentally sensitive locations are not acceptable for mass burial,” he says.

Proximity to water sources, wetlands, wells, shallow water tables and bedrock are important considerations. A statewide assessment of conditions in Iowa, for example, revealed that as much as 30-40% of the state is not well suited for mass burial.

To assist producers, the Iowa Department of Natural Resources has developed a livestock burial zone map identifying locations where conditions are likely to limit or prevent approval of mass burial. The map can be viewed at http://csbweb.igsb.uiowa.edu/imsgate/introduction/home.asp. Before assuming your state would allow mass burial of livestock, make sure you check with state Natural Resources Conservation Service for details. In Iowa, the state DNR has developed a map of all farm sites that can be referred to in order to decide if burial is advisable.

Other state and federal agencies are taking similar steps, Glanville says. The Kansas Department of Health and Environment offers a program to help owners of large livestock operations identify and preplan burial sites for emergency disposal.

“Many producers assume that landfills will accept their dead animals in an emergency. But much depends on the number of carcasses involved, and on the size of the landfill, how it is equipped, and the amount of cover soil available.

“As a result, some landfills are willing to accept large numbers of carcasses, while others are not. In general, large municipal landfills will be better equipped to handle large-scale carcass disposal than most small county landfills,” he says.

The cause of death can also enter into the decision. Due to public concern about disease transmission, British Columbia, Canada closed their gates to poultry producers during an avian influenza outbreak in 2004.

For off-site disposal options such as landfills, follow rules requiring carcasses to be hauled in leakproof, covered vehicles that prevent contamination of public roadways.

Incineration: Serious air pollution concerns caused by incineration of carcasses during the foot-and-mouth disease outbreak in Great Britain led to an immediate outcry and rapid ban of open burning.

“As a result, many environmental agencies are now reluctant to permit uncontrolled burning of carcasses, and will instead require use of air curtain incinerators or other specialized methods that can meet air quality regulations,” Glanville states.

Composting: “Many hog farmers already use composting for disposal of routine mortalities, and it can be used for emergencies as well, but producers are likely to be surprised by the significantly greater amounts of cover material needed,” says Glanville.

Since emergency composting is usually done in unsheltered windrows, it is more prone to saturation which can lead to serious odors and to heat loss caused by cold winds. Both conditions call for thicker layers of sawdust, ground cornstalks or similar cover materials to insulate the pile and to absorb water before evaporation.

If you plan to use cornstalks, grind prior to use or the compost may become too porous and this can lead to serious odor and fly problems.

Rendering: Many producers do not have access to a rendering service anymore. “If you plan to include rendering in your emergency disposal plan, be sure to discuss the size of your operation with your rendering service provider, Glanville asserts.

Sudden loss of a large herd could impose a surge load that your rendering plant may not be able to handle. Discuss emergency trucking options with your renderer as well.

“We don't like to think about it, but barn fires, flooding, ventilation failures, roof collapses and even disease outbreaks are more common than we like to admit. And when it happens, it's too late to spend time researching the best disposal options,” Glanville says.

Before developing an emergency disposal plan, it's important to check with state agricultural and/or environmental agencies about their policies.

California, for example, does not permit composting of mammals (only poultry) for routine or emergency disposal.

Some states also put a weight limit on carcass size for composting.

The cause of death can also play an important role in choosing a disposal method. Some states permit composting for non-disease-related deaths, but may not permit it if the cause of death is a highly contagious disease.

Composting has become virtually the method of choice for a number of U.S. producers to conveniently dispose of dead pigs.

For many producers, composting is an attractive choice because they can manage mortalities promptly, avoiding delays that sometimes occur with rendering.

“The composting process is not complicated,” says Tom Glanville, professor and Extension engineer in the Department of Agricultural and Biosystems Engineering, Iowa State University. ‘But there are a couple of key points to keep in mind that can greatly improve composting performance and help avoid problems.”

Excess moisture is the most frequent cause of mortality composting problems. It causes slow carcass decomposition, increases odor and leaching of pollutants into the soil.

Use bins with roofs to avoid excess moisture. Bins also help retain heat and discourage rodents and scavengers from disturbing the piles.

Bin systems need not be expensive. An old corn crib, abandoned shed or similar facility can keep capital costs low, he says.

The second main cause of excess moisture is overloading the compost with too many carcasses. “Every 1,000 lb. of carcass contains about 650 lb. of water,” says Glanville, “so stacking carcasses too close together, without separating them with a sufficiently thick layer of absorptive material such as sawdust or ground cornstalks, can lead to excessive compost wetness even during seasons when rainfall is not a problem.”

To avoid this problem, be sure to use at least 12 in. of absorptive material in the base of the bin, and 6-9 in. of the same material between carcasses in the same layer, and between adjacent layers of carcasses. Position carcasses at least 9-12 in. away from the edge of the pile to avoid leakage of liquid through the sidewalls.

But if turning is done too early, it can cause unnecessary odor releases and fly problems.

Time of turning depends on the size of the carcasses. If a bin is loaded mainly with small carcasses from the farrowing house or nursery, an initial heating cycle of as little as 30 days is likely to be adequate.

For larger carcasses, waiting 60-90 days before the initial turning is advised.